Formatting is bad on this site so I can't include the tables but each JJClass has acceleration curves

Class 2 through Class 5 JJ (20-85 tons)
Vert acceleration increases by 100 (the units are not listed) for each JJ added
Horizontal acceleration increases by 95 (the units are not listed) for each JJ added
Heat generation 0.50 for every JJ added

for Class 1 (90-100 tons)
Vert acceleration increases by 250 for each JJ added
Horizontal acceleration increases by 95 for each JJ added
Heat generation 0.50 for each JJ added

I would also point out that according to the technical manual a spider jumps 240m in a 10 second interval (24 m/s). Assuming falling from gravity from 76m, then from the apex it would take 3.9383 seconds to reach the ground. That means its time to reach its maximum height took 10-3.9383 = 6.0617 seconds. That means it had anl initial vertical velocity of 12.54m/s.

Meanwhile if it traveled 240m in 10 seconds its horizontal velocity was 24 m/s. So:

How they are doing this is trickier but at least this is a jumping off point. (for scale 27m/s is 97.2kph, and the horizontal speed is 86.4m/s). A spider is ~9 meters tall so its top height is little less than 9 times its height.

The next step is to apply burn times to see how the game compares to these equations. It may be that initial velocity relative to burn time needs to be adjusted.

Burn time for spider in game is 28 seconds. Considering to reach the apex should have taken 6.5 sec and descent 3.5 sec the vi is likely set wrong. So you would need to reduce burn time and increase Vi

I finished in game testing. The JJ type and weight of the mech don't change the statistic similar to tabletop.

Burn time: Only 3.5seconds no matter how many JJ you have. More JJ add to vertical velocity but not burn time

Height: Increases by slightly less than 6m per JJ after the first JJ, the first JJ gets you to 35m.
* The problem is that you can't use all your JJ to reach that height since you have to worry about fall damage.
* In BattleTech TT they can raise you up 1 mech height about 9meters of elevation per JJ. That means initial height of 8m + 9x8 means a spider could jump 79m. In game it I listed as 76m so very close.
Also in TT you can reach that peak without needing to use burn to slow down. This means to be more like tabletop there should be no fall damage.

Vertical velocity = Increases from 10m/s to 22m/s at 10JJ in an accelerating curve. This means each jump jet changes the acceleration value.

Vertical acceleration = This appears to be 2.86m/s2 for the first jump jet and an additional 0.49m/s2 for each additional jumpjet (At 8 JJ on a spider it has a vertical acceleration of 6.2m/s2. This makes sense as burn time is fixed at 3.5 seconds.

Descent time = This is how long it takes the mech to reach the ground from its maximum height. This is 2.9sec for 1JJ to 5.5sec for 8JJ. This is following a gravity acceleration pattern. The reason the game seems so floaty is that on earth those numbers should be 2.7 sec for 1 JJ and 3.9 sec for 8 JJ. That means their acceleration for gravity is calculating at 5m/s2. The biggest problem with jump jets is that descent physics appear to be running at 5m/s2 instead of 9.8m/s2. If anyone knows how to mod this value then that would make huge difference.

The other issue appears to be with Horizontal movement. Per TT you should cover 30m per JJ. So 8JJ would move you 24m/s or 86.4kph (which matches technical readout for the spider). By jumping from the side of a fixed building while stationary and measuring the distance with the sight I have found that each JJ increases horizontal distance with an initial curve and then linear component suggesting initial acceleration followed by steady movement once JJ stop burning. Overall the linear component moves you 20m per JJ added. 8JJ move you 130m total which is equivalent given the jump time to 52kph. While this is much slower than the TT listed values the game is different and you continue to move at your initial running speed. However it is odd. If your run speed is less than lower then the velocity is additive. However if your run speed is greater their is an inflection point at which you lose velocity (Spider with <4JJ loses velocity while a spider with 5 or more JJ gains velocity while using JJ. This part is weird and makes it hard to see if horizontal distance is correct.

After further testing it seems like I am not going to be able to edit engine gravity which is 5m/s2 vs real world 9.8m/s2 unless PGI externalizes that variable. That is a bummer. However, have found the following:

1. Vi is initial velocity when you use JJ. It the has the JJacceleration curves(z = vertical, xy = horizontal) applied to this. What is fascinating is that you can set this to 0 and by adjusting the curves you can still have JJ work properly. This is more true to the real-world since the only Vi in the real-world would be your mech running not a random number. However, setting acceleration curves to something reasonable and then adjusting this value is simpler.

Steps for modding for tabletop rules:
1. Set a commando (9m tall) model in your test map and scale to the height you want to jump (10m per JJ).
2. Set your burn time which roughly equates to your time to reach that height (I chose 2 seconds, shorter was hard to control)
3. Adjust your vi or JJacceleration z curve to match the height of the commando, fully use the burn time
4. Set your JJacceleration xy curve to match the horizontal distance you want to jump, jump from the commando and use your sights to measure until it is correct (for a spider 240m)
5. Add enough burn time to avoid fall damage from that height (0.5-1 seconds)
6. Set the JJ regeneration time to 10 seconds (one turn) - Jump time (have to measure with a stopwatch)